import sys
read=sys.stdin.buffer.read
readline=sys.stdin.buffer.readline
readlines=sys.stdin.buffer.readlines

class UnionFind:
    def __init__(self, n):
        self.n=n
        self.par=[-1]*n
    def find(self, x):
        if self.par[x]<0:
            return x
        self.par[x]=self.find(self.par[x])
        return self.par[x]
    def unite(self, x, y):
        x=self.find(x)
        y=self.find(y)
        if x==y:
            return False
        if self.par[x]<self.par[y]:
            x, y=y, x
        self.par[y]+=self.par[x]
        self.par[x]=y
        return True
    def same(self, x, y):
        return self.find(x)==self.find(y)
    def size(self, x):
        return -self.par[self.find(x)]

n=int(readline())
if n==0:
    print(1)
    exit()
m=map(int, read().split())
xy=list(zip(m, m))
uf=UnionFind(n)
for i, (xi, yi) in enumerate(xy):
    for j, (xj, yj) in enumerate(xy[:i]):
        if (xi-xj)*(xi-xj)+(yi-yj)*(yi-yj)<=100:
            uf.unite(i, j)
mx=0
for i, (xi, yi) in enumerate(xy):
    for j, (xj, yj) in enumerate(xy[:i]):
        d=(xi-xj)*(xi-xj)+(yi-yj)*(yi-yj)
        if mx<d and uf.same(i, j):
            mx=d
import math
print('{:.7f}'.format(2.0+math.sqrt(mx)))